1. Technical Field
This invention relates to electronic load circuits, and more particularly to a low-voltage, high-current load circuits for use in testing power supplies or the like for computers and systems of this type.
2. Description of the Related Art
In the design and production of power supply modules for computer systems and the like, it is necessary to have load circuits which simulate the operation of the computer itself in the way the voltage and current levels presented by the load vary with time and other conditions. For example, the load presented to the power supply by the computer system may switch between high-current and low-current when the computer goes into a power-down or sleep mode as power management mechanisms go into effect. Or, current spikes may occur when starting up equipment such as a hard drive, or at boot-up when large capacitive loads are being charged. Likewise, power-up self test creates a widely variable load as all of the peripheral equipment is exercised.
Previous load circuits used for test purposes in the manufacture of computer systems or the like have not been able to operate at low voltages such as the supply voltage levels being specified for contemporary microprocessor chips and memory chips. For example, supply voltage levels of 3.3V have ben used for some time, and levels of 1.7v or 1.5V are coming into common usage. At these low voltage levels, and at high currents of sometimes hundreds of amps, the available equipment is not able to accurately simulate varying load currents, nor represent the loading exhibited by a computer system.